The research aims to formulate and validate molecular models of sugar transport across cell membranes by applying kinetic, biochemical and genetic methods to the study of (a) Beta-galactoside transport in E. coli, (b) hexose transfer in human erythrocytes and (c) hexose transfer dependent upon insulin in rat adipose cells. Studies in E. coli include kinetic experiments to determine the relationship of the rate constants involved in the mobile carrier model of facilitated diffusion; biochemical studies to define the nature of energy coupling for active accumulation as well as the biosynthesis and integration of the product of the y gene as a functional carrier; and genetic studies to design suitable mutants for these functions. Studies with human erythrocytes and rat adipose cells aim to provide the kinetic parameters for facilitated diffusion and to label specifically and isolate the membrane carrier elements. The effects of insulin upon the transport mechanism in rat adipose cells will be studied.